1. Field of the Invention
The present invention relates to a management apparatus, an image forming apparatus maintenance system including multiple image forming apparatuses, such as copiers, printers, and facsimile machines, and a management apparatus communicably connected to the image forming apparatuses via a communication network, and a management method that manages multiple image forming apparatuses via a communication network.
2. Description of the Related Art
In an electrophotographic image forming apparatus, a surface of a photoconductor serving as a latent image carrier is charged by a charging device and exposed to light by an exposure device to form an electrostatic latent image, and a visible image is formed on the electrostatic latent image with charged fine particles of toner by a development device. The charging device may be either a non-contact charging device or a contact charging device. The non-contact charging device includes, for example, a corona charging device which uses corona discharge generated by a relatively high voltage applied to a wire electrode. The contact charging device charges the surface of the photoconductor by bringing a voltage-applied conductive brush or roller into contact with the surface of the photoconductor.
The non-contact charging device generates, as discharge products, a relatively large amount of ozone and nitrogen oxide, causing an abnormal image. Meanwhile, the contact charging device produces a smaller amount of ozone and nitrogen oxide than the non-contact charging device, but causes wear of a photoconductor surface layer resulting in a reduction in life of the photoconductor and variation in charging performance due to the usage environment. Based on a comparison of the features of the two types of charging devices, the non-contact charging device is recognized as the better choice in some cases.
The discharge products generated by the use of the charging device reduce the electrical resistance of the surface of the photoconductor and contaminate the charging device, thereby causing insulation failure and discharge failure. Particularly, when the image forming apparatus is placed at rest in a high-humidity environment for a certain period of time after extended use of the charging device, foreign conductive substances, such as water-soluble matter in the discharge products generated by the charging device, adhere to and contaminate the surface of the photoconductor. With this contamination of the surface of the photoconductor, the charge on the surface of the photoconductor formed with the electrostatic latent image moves along the surface of the photoconductor, thereby causing an abnormal image, such as a tailing image.
The image forming apparatus may be configured such that, if the values of the rest time following the last image forming operation, the use history of the photoconductor, the use history of the charging device, and the relative humidity near the photoconductor exceed their respective thresholds, a preliminary photoconductor rotation operation is performed for a predetermined time when the image forming apparatus is powered on or returns from an energy-saving mode. With the preliminary photoconductor rotation operation, the discharge products adhering to the surface of the photoconductor are scraped off by a developer or a cleaning member, thereby suppressing the occurrence of an abnormal image.
Alternatively, the image forming apparatus may be configured to supply a direct-current voltage lower than a discharge starting voltage to a charging roller, measure a direct current value by using a measuring circuit, and determine, on the basis of the measurement result, whether or not a tailing image would be formed on a photoconductor drum. If it is determined that a tailing image would be formed on a photoconductor drum, the image forming apparatus may execute a tailing image suppression mode in which a heater is turned on to reduce the relative humidity near the surface of the photoconductor drum and thereby suppress the tailing image.
Still alternatively, the image forming apparatus may be configured to, in an anti-aging operation of polishing the surface of the photoconductor drum by bringing a cleaning member into contact with the rotating photoconductor drum carrying toner, determine the level of possibility of the tailing image from the result of reading a density detection pattern image formed on the photoconductor drum before the anti-aging operation, and change the length of the anti-aging operation in accordance with the level of possibility. In the image forming apparatus, the discharge products adhering to the surface of the photoconductor drum are scraped off by the developer or the cleaning member in the anti-aging operation, thereby suppressing the occurrence of an abnormal image.
In general, to predict the occurrence of an abnormal image such as a tailing image due to the generation of the discharge products, a photoconductor surface contamination level is predicted from internal information of the image forming apparatus, i.e., information useful for the prediction. The photoconductor surface contamination level is an index value indicating the level of contamination of the surface of the photoconductor due to the discharge products. Then, if the photoconductor surface contamination level exceeds a specified value, it is determined that the abnormal image due to the generation of the discharge products would occur in the near feature, and a process of reducing the contamination of the surface of the photoconductor is performed. The process corresponds to, for example, the preliminary photoconductor rotation operation or the anti-aging operation described above.
If the accuracy of predicting the photoconductor surface contamination level is improved, the accuracy of preventing the occurrence of an abnormal image due to the generation of the discharge products is improved. Further, if the accuracy of predicting the photoconductor surface contamination level is improved, it is possible to perform the process of reducing the contamination of the surface of the photoconductor as close as possible to actual occurrence of an abnormal image. Due to the contamination reduction process, therefore, the deterioration of the surface of the photoconductor is suppressed.
The process of predicting the occurrence of an abnormal image (i.e., the photoconductor surface contamination level) due to the generation of the discharge products has been improved by continuous research and development and continuous data collection, and new prediction processes capable of performing more accurate prediction have been proposed. The latest prediction process thus improved or newly proposed is capable of performing more accurate prediction than past prediction processes, and thus is desired to be applied to existing image forming apparatuses already on the market.
The process of predicting the photoconductor surface contamination level due to the generation of the discharge products may be performed inside individual image forming apparatuses. To apply a new prediction process to image forming apparatuses released on the market before the improvement and development of the new prediction process, however, it is necessary to, for example, individually visit locations where the image forming apparatuses are installed and perform updating work for applying the new prediction process to the image forming apparatuses. Since a huge number of image forming apparatuses are on the market, it is difficult to individually visit each and every location where the image forming apparatuses are installed and perform the work for applying the new prediction process to the image forming apparatuses.
Meanwhile, the image forming apparatus may be configured to be communicable with an external apparatus via a communication network. If the image forming apparatus is thus configured, it is possible to perform the updating work for applying the new prediction process by remote control via the communication network, with no need to individually visit the locations with the image forming apparatuses installed. To appropriately perform the updating work, however, it is preferable to perform the updating work with the image forming operation stopped. The updating work, therefore, causes a downtime during which the image forming operation is prevented. Such a downtime reduces image formation productivity, and thus is desired to be avoided as much as possible.
Moreover, among the various ways of predicting a variety of abnormalities occurring in the image forming apparatus, the prediction of the latent image carrier surface contamination level due to the generation of the discharge products is particularly affected by the usage environment of the individual image forming apparatus. Since individual image forming apparatuses are used in different usage environments, it is difficult to improve the prediction accuracy by conducting reproductive experiments in, for example, a laboratory. To improve the accuracy of predicting the latent image carrier surface contamination level, therefore, it is desired to collect information useful for the prediction (particularly, information useful for the prediction corresponding to a period immediately before the occurrence of an abnormal image due to the discharge products) in the image forming apparatus operating in an actual usage environment, and to feed back the information to the prediction process. Further, it is desired to promptly perform the feedback upon collection of the information. If the feedback to the prediction process is performed every time the information useful for the prediction is collected, however, the frequency of updating the prediction process is increased, since the time for collecting the information substantially varies among image forming apparatuses. This configuration therefore causes an increase in frequency of downtime and a further reduction in image formation productivity.